Neste trabalho, a microextração em fase líquida com membrana cilíndrica oca (HF-LPME), a microextração líquido-líquido dispersiva (DLLME) e a microextração em fase sólida na configuração de um filme delgado (SPME/TFME) foram empregadas como técnicas de microextração para a preparação de amostras microssomais no estudo de metabolismo in vitro de fármacos quirais com diferentes características ácido-base. Para análise empregou-se a cromatografia líquida de alta eficiência (HPLC) com detector por absorção no UV e a cromatografia líquida acoplada à espectrometria de massas (LC-MS-MS). O fármaco neutro isradipina (ISR) foi o primeiro a ser abordado. Um método estereosseletivo empregando HFLPME- HPLC foi desenvolvido para a determinação dos enantiômeros da ISR e seu principal metabólito (um derivado piridínico da isradipina - PDI) em fração microssomal isolada de fígado de ratos. Os analitos foram extraídos de 1 mL de meio microssomal utilizando o procedimento HF-LPME na configuração duas fases, tendo o solvente acetato de hexila como fase aceptora. Pela primeira vez, o PDI e os enantiômeros da ISR foram resolvidos numa mesma corrida cromatográfica. Para esta separação foi utilizada uma coluna Chiralpak AD® e hexano:2-propanol:etanol (94/04/02, v/v/v) como fase móvel, na vazão de 1,5 mL min-1. A ISR e o PDI foram detectados em 325 nm e o padrão interno, oxibutinina, foi detectado em 225 nm. A validação do método mostrou valores de recuperação de 23% para o PDI e 19% para cada enantiômero da ISR, 50 ng mL-1 como limite de quantificação (LOQ) para todos os analitos e linearidade entre 50-5000 ng mL-1 e 50-2500 ng mL-1 para o PDI e cada enantiômero da ISR, respectivamente. O método desenvolvido e validado foi aplicado em um estudo de metabolismo in vitro, utilizando microssomas hepáticos de ratos, mostrando que o (+)-(S)-ISR foi preferencialmente metabolizado. Do mesmo modo que para a ISR, um método analítico empregando HF-LPME-HPLC no modo três-fases foi desenvolvido para a análise estereosseletiva concomitante do bufuralol (BF) e dos seus principais metabólitos 1\'- oxobufuralol (1\'-Oxo-BF) e 1\'-hidroxibufuralol (1\'-OH-BF) em preparações microssomais. As análises por HPLC foram conduzidas empregando uma coluna Chiralcel OD-H® com fase móvel composta por hexano:2-propanol:metanol:dietilamina (97,5/2,0/0,5/0,5, v/v/v/v), na vazão de 1,5 mL min-1 e detecção em 248 nm e 273 nm. As condições otimizadas da HFLPME foram: n-octanol como solvente orgânico, ácido acético 0,2 mol L-1 como fase aceptora, fase doadora com pH ajustado em 13 e agitação de 1500 rpm por 30 min. O método foi validado e apresentou valores de recuperação entre 63 - 69% para os analitos e mostrou-se linear entre 100 - 5000 ng mL-1 para cada enantiômero do 1\'-Oxo-BF e 100 - 2500 ng mL-1 para cada estereoisômero do 1\'-OH-BF (r > 0,99), com LOQ de 100 ng mL-1 para todos os analitos. O método desenvolvido e validado foi aplicado em um estudo de metabolismo in vitro do BF utilizando microssomas hepáticos de ratos, que mostrou formação predominante do (S)-1\'-Oxo-BF e do (R,R)-1\'-OH-BF. Um segundo fármaco básico abordado neste trabalho foi a ranolazina (RNZ). Para a análise enantiosseletiva da RNZ e de um de seus metabólitos (desmetil ranolazina - DRNZ) em fração microssomal isolada de fígado de ratos, foi desenvolvido um método estereosseletivo empregando a DLLME-LC-MS-MS. Os analitos foram extraídos de 0,5 mL de meio microssomal utilizando o procedimento DLLME, tendo o clorofórmio como solvente extrator e acetona como solvente dispersante. Pela primeira vez os enantiômeros da RNZ e DRNZ foram resolvidos numa mesma corrida cromatográfica. ii Para esta separação foi utilizada uma coluna Chiralcel OD-H® e hexano:etanol (60/40, v/v) e 0,05% de dietilamina como fase móvel, na vazão de 1,0 mL min-1. A validação do método mostrou valores de recuperação em torno dos 55 e 45% para os enantiômeros da RNZ e DRNZ, respectivamente. Os LOQ foram de 25 ng mL-1 para cada enantiômero da RNZ e 10 ng mL-1 para cada enantiômero da DRNZ. A linearidade foi estabelecida entre 10-1000 ng mL-1 e 25-2500 ng mL-1 para cada enantiômero da DRNZ e RNZ, respectivamente. O método desenvolvido e validado foi aplicado em um estudo de metabolismo in vitro utilizando microssomas hepáticos de ratos, mostrando que a metabolismo da RNZ foi enantiosseletivo. Finalmente, um método analítico empregando a SPME/TFME-LC-MS-MS foi desenvolvido para a análise simultânea do fármaco anfótero repaglinida (RPG) e dois dos seus principais metabólitos, a 2-despiperiril-2-amino-repaglinida (DA-RPG) e a 2-despiperidil-2-(5- carboxipentilamina)-repaglinida (DC-RPG) em fração microssomal isolada de fígado humano. A SPME/TFME foi conduzida com o auxílio do equipamento Multi Sampler SPME nas seguintes condições: pré-condicionamento dos blades com 1 mL de uma solução metanol:água (50/50, v/v) por 30 min, 60 min de extração e 90 min de dessorção com 1 mL de fase móvel. A análise por LC-MS-MS foi feita empregando uma coluna cromatográfica C18 em modo reverso, com fase móvel composta por acetonitrila:água (50/50, v/v) e 0,1% de ácido acético, na vazão de 0,5 mL min-1. A validação do método mostrou valores de recuperação acima dos 80% para todos os analitos. O LOQ foi de 2 ng mL-1 para todos os analitos, sendo o método linear no intervalo 2-1000 ng mL-1 para a RPG e 2-500 ng mL-1 para a DA-RPG e DC-RPG. Os analitos foram estáveis durante todo o protocolo analítico e de metabolismo. O método validado foi aplicado em um estudo de metabolismo in vitro utilizando microssomas hepáticos de humanos, mostrando que o perfil metabólico da RPG e a taxa de formação da DA-RPG e DC-RPG é alterada em função da concentração de proteínas microssomais no meio de incubação e também em função do tempo de incubação. Além disso, os resultados mostrama possibilidade de haver diversos outros metabólitos que não foram monitorados. / In the present work, the microextraction techniques hollow-fiber liquid phase microextraction (HF-LPME), dispersive liquid-liquid microextraction (DLLME) and solid phase microextraction based on thin film (SPME/TFME) were used as sample preparation techniques to study the in vitro metabolism of chiral drugs with distinct acid-base characteristics. High-performance liquid chromatography (HPLC) with UV detection and liquid chromatography coupled to mass spectrometry (LC-MS-MS) were used for the analyses. An enantioselective liquid chromatographic method using two-phase hollow- fiber liquid-phase microextraction (HF-LPME-HPLC) was developed for the determination of isradipine (ISR) enantiomers and its main metabolite (pyridine derivative of isradipine - PDI) in microsomal fraction isolated from rat liver. The analytes were extracted from 1 mL of microsomal medium using a two-phase HF-LPME procedure with hexyl acetate as the acceptor phase, 30 min of extraction and sample agitation at 1500 rpm. For the first time, ISR enantiomers and PDI were resolved. For this separation, a Chiralpak AD® column with hexane:2-propanol:ethanol (94/04/02, v/v/v) as mobile phase at a flow rate of 1.5 mL min-1 were used. The column was kept at 23 °C ± 2. The drug and metabolite detection was performed at 325 nm and the internal standard oxybutynin was detected at 225 nm. The recovery rates were 23% for PDI and 19% for each ISR enantiomer. The method presented quantification limits (LOQ) of 50 ng mL-1 and it was linear over the concentration range of 50-5000 ng mL-1 and 50-2500 ng mL-1 for PDI and each ISR enantiomer, respectively. The validated method was employed to an in vitro metabolism study of ISR using rat liver microsomal fraction, showing that (+)-(S)-ISR is preferentially metabolized. In the same way, a three-phase HF-LPME-HPLC method for the stereoselective determination of bufuralol metabolites, 1\'-oxobufuralol (1\'-Oxo-BF) and 1\'-hydroxybufuralol (1\'-OH-BF), in microsomal preparations is described for the first time. The HPLC analysis was carried out using a Chiralcel OD-H® column with hexane:2-propanol:methanol (97.5/2.0/0.5, v/v/v) plus 0.5% diethylamine as the mobile phase, and UV detection at 248 and 273 nm. The HF-LPME optimized conditions involved: n-octanol as the organic solvent, 0.2 mol L-1 acetic acid as the acceptor phase, donor phase pH adjusted to 13, sample agitation at 1500 rpm and extraction for 30 min. By using this extraction procedure, the recovery rates were in the range of 63- 69%. The method was linear over the concentration range of 100-5000 ng mL-1 for each enantiomer of 1\'-Oxo-BF and of 100-2500 ng mL-1 for each stereoisomer of 1\'-OH-BF. The quantification limits were 100 ng mL-1 for all analytes. The validated method was used to assess the in vitro metabolism of bufuralol using rat liver microsomal fraction that demonstrated predominant formation of (S)-1\'-Oxo-BF and (R,R)-1\'-OH-BF. A second basic drug addressed in this thesis is ranolazine (RNZ). For the chiral analysis of RNZ and one of its metabolites (desmethyl ranolazine - DRNZ) in microsomal fraction isolated from rat liver, an analytical enantioselective method using DLLME-LC-MS-MS was developed. The analytes were extracted from 0.5 mL of microsomal medium by DLLME. Chloroform was the extractor solvent and acetone the dispersive solvent. The enantiomers of RNZ and DRNZ were analyzed simultaneously for the first time using a Chiralcel OD-H® column and hexane:ethanol (60/40, v/v) plus 0.05% diethylamine as mobile phase at a flow rate of 1.0 mL min-1. Method validation showed recoveries in the order of 55 and 45% for the enantiomers iv of RNZ and DRNZ, respectively. The LOQs were 25 ng mL-1 for each RNZ enantiomers and 10 ng mL-1 for each DRNZ enantiomers. Linearity was established between 10-1000 ng mL-1 and 25-2500 ng mL-1 for each DRNZ and RNZ enantiomers, respectively. The validated method was employed to an in vitro metabolism study of RNZ using rat liver microsomal fraction, showing that the metabolism of RNZ is enantioselective. Finally, an analytical method was developed employing SPME/TFME-LC-MS-MS for the simultaneous analyses of the anphoteric drug repaglinide (RPG) and two of the its main metabolites 2-despiperidyl- 2-amino repaglinide (DA-RPG) and 2-despiperidyl-2-(5-carboxypentylamine) repaglinide (DC-RPG) in human microsomal fraction. The SPME/TFME procedure was carried out with the support of \"Multi Sampler SPME\" under the following conditions: conditioning of the blades with 1 mL of methanol:water (50/50, v/v) for 30 min, 60 min for extraction and 90 min for desorption with 1 mL of mobile phase. The LC-MS-MS analyses were performed using a C18 column under reversed phase conditions, with the mobile phase of acetonitrile:water (50/50, v/v) plus 0.1% acetic acid at a flow rate of 0.5 mL min-1. The method validation showed recoveries over 80% for all analytes. The LOQ was 2 ng mL-1 for all analytes, and the method was linear over the concentration range of 2 e 1000 ng mL-1 for RPG and of 2 a 500 ng mL-1 for DA-RPG and DC-RPG. The validated method was used to assess the in vitro metabolism profile of RPG by using human liver microsomes. These studies showed that the rate of formation of DA-RPG and DC-RPG depends on both microsomal protein concentration in the incubation medium and the incubation time. Furthermore, the results highlighted the possibility of formation of several other metabolites which have not been monitored.

Thesis advisor: James P. Morken / This dissertation details the development, application and study of new palladium-catalyzed carbon-carbon bond forming strategies that generate synthetically useful enantioenriched small molecules. Controlled by a bidentate phosphine ligand, these transformations are thought to operate through a unique 3,3'-reductive elimination that leads to high regio- and stereoselectivity. Specifically, Chapter 1 introduces background on prior work that led to the first allyl-allyl coupling to deliver branched 1,5-dienes, and presents new computational studies on the origins of regioselectivity with mono- and bidentate ligands. Building on these studies, Chapter 2 describes the development of a diastereoselective allyl-allyl coupling of substituted allylboron reagents with allylic chloride electrophiles. To extend the scope of allyl-allyl coupling, Chapter 3 details further reaction optimization and mechanistic studies that have allowed for increasingly congested bond formations. In Chapter 4, a related allyl-propargyl coupling to give enantioenriched 1,5-enynes through stereospecific reactions and kinetic resolution is presented. These developments are accompanied by laboratory and computational data that provide a deeper understanding of reaction mechanisms and the origins of regio- and stereoselectivity. / Thesis (PhD) — Boston College, 2014. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

Thesis advisor: Amir H. Hoveyda / In the course of a total synthesis of quebrachamine, we were faced with a late-stage enantioselective ring-closing metathesis that could not be promoted by any of the state-of-the-art chiral metathesis catalysts. To overcome this deficiency, we designed and developed a new class of catalysts based on mechanistic and theoretical principles. The new catalysts contain a stereogenic metal center and display unprecedented levels of reactivity and selectivity in enantioselective olefin metathesis, enabling us to complete our planned synthesis of quebrachamine. We have also discovered that non-productive metathesis reactions with stereogenic-at-Mo catalysts, generated and used in situ as a mixture of diastereomers, are crucial to the efficiency and enantioselectivity of the ring-closing metathesis reactions. Specifically, our studies have indicated that the two diastereomers of catalyst are in rapid equilibrium due to non-productive metathesis with ethylene, generated as the desired ring-closing reaction proceeds, thereby establishing a reaction manifold that is under Curtin-Hammett control. Finally, in our efforts to prepare air-stable precursors to stereogenic-at-Mo olefin metathesis catalysts, we have examined the addition of N,N-chelating ligands to Mo bis-pyrrolide complexes. Upon addition of 2,2′-bipyridyl to bis-dimethylpyrrolide Mo complexes, rather than the expected octahedral chelate, a five-coordinate monopyrrolide alkylidyne complex is generated. The complex displays good air-stability and efficiently serves as a precursor to stereogenic-at-Mo alkylidene catalysts; several alkylidyne complexes have been prepared. / Thesis (PhD) — Boston College, 2010. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

Thesis advisor: Amir H. Hoveyda / Formation of C-C bonds is an invaluable tool for the construction of materials, pharmaceuticals, natural products, and the building blocks of life. Although great strides in this area have been made, there remain several limitations in regio-, site-, and enantioselective additions of carbon-based nucleophiles. Solving these challenges by expanding the scope, efficiency, and selectivity of alkyl, aryl, heteroaryl, vinyl, and alkynyl additions to carbon-based electrophiles is the topic of this dissertation. / Thesis (PhD) — Boston College, 2013. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

Thesis advisor: Amir H. Hoveyda / Chapter One: An overview of Cu-catalyzed enantioselective allylic substitutions with organometallic reagents. Chapter Two: Development of Cu-catalyzed enantioselective allylic alkylations of allylic chlorides with Grignard reagents for the formation of all-carbon quaternary stereogenic centers is disclosed. Chapter Three: Development of Cu-catalyzed enantioselective allylic substitutions of allylic phosphates with alkyl, aryl, and heterocyclic aluminum reagents for the formation of quaternary stereogenic centers is discussed. / Thesis (MS) — Boston College, 2010. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

Thesis advisor: James P. Morken / This dissertation will present four main projects focused on stereoselective construction of borylated compounds as well as their applications in asymmetric syntheses. The first two projects describe the development of a catalytic conjunctive cross-coupling reaction. By merging three simple starting materials, an organolithium reagent, an organoboronate, and an organic electrophile, a synthetically valuable secondary boronate is furnished by the conjunctive cross-coupling in an efficient and enantioselective fashion. Next, this strategy is expanded to synthesize severely hindered tertiary boronates, a synthetic challenging but powerful building block to access a variety of quaternary stereocenters. The third project presents a platinum-catalyzed enantioselective diboration of alkenyl boronates to furnish a broad range of 1,1,2-tris(boronates) products. A deborylative alkylation of the 1,1,2-tris(boronates) leads to a variety of internal vicinal bis(boronates) with high diastereoselectivity. In the final chapter, a general and practical synthesis of alkenyl boronates via the boron-Wittig reaction is disclosed. Utilizing readily accessible geminal bis(boronates) and aldehydes, a broad range of disubstituted and trisubstituted alkenyl boronates are afforded with good yield and stereoselectivity. / Thesis (PhD) — Boston College, 2017. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

Thesis advisor: Amir H. Hoveyda / Chapter 1. In this chapter, the ability of chiral bidentate N-heterocyclic carbenes (NHCs) to activate alkylmetal reagents directly in order to promote C&#8210;C bond forming reactions in the absence of a Cu salt is presented. Highly regio- and enantioselective Cu-free allylic alkylation reactions of di- and trisubstituted allylic substrates with organomagnesium, organozinc, and organoaluminum reagents are demonstrated. Chiral bidentate sulfonate-bearing NHC-Zn and NHC-Al complexes are isolated and fully characterized. Based on crystal structures of these catalytic complexes, mechanistic details regarding Cu-free allylic alkylations with alkylmetal reagents are proposed. Chapter 2. New methods for efficient and highly enantioselective Cu-catalyzed allylic alkylation reactions of a variety of trisubstituted allylic substrates with alkylmagnesium and alkyl-, aryl-, 2-furyl-, and 2-thiophenylaluminum reagents are presented. Transformations are promoted by a chiral NHC complex in the presence of commercially available, inexpensive and air stable CuCl2*H2O. Enantiomerically enriched compounds containing difficult-to-access all-carbon quaternary stereogenic centers are obtained. Chapter 3. New methods for highly site- and enantioselective Cu-catalyzed allylic alkylation reactions of allylic phosphates with vinylaluminum reagents are presented. The requisite vinylaluminums are prepared by reaction of readily accessible terminal alkynes with DIBAL-H and used directly without further purification. Vinyl additions are promoted in the presence of a chiral bidentate sulfonate-based NHC complex and a Cu salt. The desired SN2' products are obtained in >98% E selectivities, >98% SN2' selectivities, >98% group selectivities (<2% i-Bu addition) and high enantioselectivities. The enantioselective total synthesis of the natural product bakuchiol highlights the versatility of the one-pot hydroalumination/Cu-catalyzed enantioselective allylic vinylation process. Chapter 4. Efficient and highly site-selective Cu-catalyzed hydroboration reactions of 1,2-disubstituted aryl olefins with bis(pinacolato)diboron (B2(pin)2) are presented. Transformations are promoted by an NHC-Cu complex in the presence of MeOH, affording only secondary &#946;-boronate isomers. A Cu-catalyzed method for the synthesis of enantiomerically enriched secondary alkylboronates promoted by chiral NHC complexes is disclosed. Chapter 5. A new method for efficient and site-selective tandem Cu-catalyzed copper-boron additions to terminal alkynes with B2(pin)2 in the presence of an NHC-Cu complex is demonstrated. In a one-pot process, Cu-catalyzed hydroboration of alkynes provides vinylboronates in situ, which undergo a second site-selective hydroboration to afford vicinal diboronates. Highly Enantiomerically enriched diboronates obtained through Cu-catalyzed enantioselective dihydroboration in the presence of chiral bidentate sulfonate-based NHC-Cu complex are obtained. The control of site selectivity in the first-stage hydroboration of alkynes is critical for efficient and highly enantioselective reactions in the tandem dihydroboration. Functionalizations of the vicinal diboronates described herein underline the significance of the current method. / Thesis (PhD) — Boston College, 2010. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

A fexofenadina (FEX) tem sido o fármaco de primeira escolha no tratamento sintomático de manifestações alérgicas, por ser um anti-histamínico dos receptores H1 de 2ª geração não sedativo. É o metabólito ativo e quiral da terfenadina (TERF), medicamento cuja produção e comercialização foram suspensas em função dos eventos adversos apresentados. Fungos têm se apresentado como uma alternativa promissora na produção de compostos com atividade biológica. Dessa forma, o objetivo desse projeto foi avaliar a capacidade de fungos em biotransformar enantiosseletivamente a terfenadina em seu metabólito ativo, a fexofenadina empregando fungos como agentes catalisadores. Para a análise enantiosseletiva da fexofenadina foi desenvolvido um método de separação cromatográfica empregando a coluna quiral Lux® cellulose-1, fase móvel constituída de água: metanol (35:65, v/v) + 0,3% trietilamina + 0,4% ácido acético, vazão de 0,5 mL min-1, com detecção em 220nm. Duas microtécnicas de preparação de amostras foram avaliadas na extração dos analitos do meio de cultura: a microextração liquido-liquido dispersiva (DLLME) e a microextração em fase liquida empregando membranas cilíndricas ocas (HF-LPME). Entre essas, a DLLME foi a microtécnica de escolha, pois forneceu melhores resultados tais como, maior valor de recuperação, cromatogramas sem picos de possíveis interferentes, maior rapidez e facilidade de preparação das amostras. As condições otimizadas da DLLME foram: clorofórmio (300 ?L) como solvente extrator, isopropanol (300 ?L) como solvente dispersor. Após a formação do ponto nuvem, as amostras foram submetidas à agitação por vórtex durante 15 segundos e centrifugação durante 10 minutos a 3000 rpm. As recuperações foram de 43% para ambos enantiômeros. O método se mostrou linear na faixa de concentração 2.0 - 15.0 ?g mL-1 para cada enantiômero da FEX (r > 0,990). O limite de quantificação foi de 2 ?g mL-1 para os enantiômeros da FEX. Dentre os sete fungos estudados (Papulaspora immersa Hotson SS13, Penicillium crustosum VR4, Mucor rouxii, Nigrospora sphaerica SS67, Fusarium oxysporum SS50, Cunninghamella echinulata var. elegans ATCC 8688A e Cunninghamella elegans NRRL 1393 ATCC 10028B) somente o fungo Fusarium oxysporum SS50 e Cunninghamella echinulata var. elegans ATCC 8688A apresentaram potencial para biotransformação da terfenadina em fexofenadina nas condições de incubação empregadas nesse trabalho. / Fexofenadine (FEX) has been the drug of choice for the symptomatic treatment of allergic manifestations, being an antihistamine H1 receptor 2nd generation non-sedating. It is the active and chiral metabolite of terfenadine (TERF), a drug whose production and marketing was suspended as a result of adverse events. Fungi have been presented as a promising alternative for the production of compounds with biological activity. Thus, the goal of this project was to evaluate the ability of fungi to biotransform asymmetric terfenadine to its active metabolite, fexofenadine using fungi as agents catalysts. For enantioselective analysis of fexofenadine a method for chromatographic separation was developed employing a chiral column Lux® cellulose -1, mobile phase water : methanol (35:65,v/v) + 0.3% triethylamine + 0.4% acetic acid, flow rate of 0.5 mL min-1, with detection at 220nm. Two sample preparation microtechnology were evaluated in the extraction of analytes from the culture medium: the dispersive liquid-liquid microextraction (DLLME) and hollow fiber liquid phase microextraction (HF- LPME). Between the two, the DLLME was the microtechnic chosen because it provided better results such as higher recovery values, chromatograms with no possible interfering peaks, greater speed and ease of sample preparation. The optimized conditions of DLLME were: chloroform (300 ?L) as extractor solvent, isopropanol (300 ?L) as disperser solvent. After the formation of the cloud point, the samples were subjected to agitation by vortexing for 15 seconds and centrifuging for 10 minutes at 3000 rpm. The recoveries were 43 % for both enantiomers. The method was linear in the concentration range from 2.0 -15.0 ?g mL-1 for each enantiomer of FEX (r > 0.990). The limit of quantification was 2 ?g mL-1 for the enantiomers of FEX. Among the seven fungi studied (Papulaspora immersa Hotson SS13, Penicillium crustosum VR4, Mucor rouxii, Nigrospora sphaerica SS67, Fusarium oxysporum SS50, Cunninghamella echinulata var. elegans ATCC 8688A e Cunninghamella elegans NRRL 1393 ATCC 10028B), only the fungi Fusarium oxysporum SS50 e Cunninghamella echinulata var. elegans ATCC 8688A showed potential for biotransformation of terfenadine in fexofenadine in the incubation conditions employed in this work.

Inspirados em reações catalisadas por enzimas a partir de micro-organismos encontrados em ambientes marinhos severos (psicrofílicos), em que a quantidade de oxigênio é restrita, observou-se que a Arthrobacter sp. CCT 7749 realizou diferentes transformações químicas mudando de condições reacionais anaeróbias para aeróbias. Dependendo da presença ou ausência de oxigênio, ambas desracemização de alcoóis ou redução de cetonas com seletividades enantiocomplementares foram realizadas pelo mesmo microorganismo. Estes conceitos foram aplicados tanto para desracemização quanto para redução enantiosseletiva de compostos contendo heteroátomos (silício, fósforo, estanho e boro). Visando a identificação molecular das enzimas responsáveis pelas reações de oxido-redução, buscou-se desenvolver uma metodologia de purificação enzimática usando diferentes técnicas. Inicialmente a lise celular da Arthrobacter sp. CCT 7749 empregando a liticase na presença de &#946;-mercaptoetanol e usando ondas ultrassônicas produziu 28 mg/mL de proteínas. A purificação da oxidorredutase ocorreu através de colunas cromatográficas de troca iônica DEAE FF, seguida por ANX FF. O extrato protéico contendo a enzima parcialmente pura apresentou atividade específica de 4,23 U/mg na oxidação do (R,S)-1-(4-metilfenil)etanol à cetona correspondente. Através do uso das técnicas native-PAGE e zimografia detectou-se uma massa molecular da enzima de &#8776;240 kDa e que provavelmente se encontrava na forma hetero-hexamérica apresentando três subunidades em ~35 kDa e três em ~45 kDa. Observou-se que, surpreendentemente, a fração protéica parcialmente pura também foi capaz de reduzir a 4-metilacetofenona obtendo-se 17% do (S)-1-(4-metilfenil)etanol com excelente excesso enantiomérico >99%. / Inspired by enzyme-catalyzed reactions with microorganisms found in harsh marine environments (psychrophilic), in which the amount of oxygen is restrict, we have shown that Arthrobacter sp. CCT 7749 can perform different chemical transformations by switching from anaerobic to aerobic reaction conditions. Depending on the presence or absence of oxygen, either alcohol deracemization or ketone reduction with enantiocomplementary selectivities can be performed by the same microorganism. These concepts were applied for both deracemization and enantioselective reduction of heteroatom-containing molecules (silicon, phosphorus, tin and boron). Aiming Enzyme purification, different techniques were employed. Cell lysate of Arthrobacter sp. CCT 7749. Was prepared using lyticase and &#946;-mercaptoethanol bu ultrasonication. Purification of this enzyme occurred through chromatographic columns of DEAE FF ion exchange, followed by ANX FF. The partially pure oxidoreductase presented specific activity of 4.23/mg in the oxidation (RS)-1-(4- methylphenyl)ethanol to the corresponding ketone. Native-PAGE and zymography have shown that the enzyme had &#8776;240 kDa molecular mass, probably in the form hetero-hexameric with 3 subunits ~35 kDa and three ~45 kDa. Surprisingly, the partially pure protein fraction was able to reduce the 4- methylacetophenone giving 17% of (S)-1-(4-methylphenyl)ethanol with excellent enantiomeric excess >99%.

A oxibutinina é um fármaco quiral empregado na forma de racemato que, após administração por via oral, sofre biotranformação hepática pronunciada levando à formação de N-desetiloxibutinina. Este metabólito apresenta atividade anticolinérgica semelhante a da oxibutinina, contribuindo com o efeito farmacológico e, também, com os efeitos adversos. Em relação às propriedades farmacocinéticas, alguns estudos prévios indicam que a biotransformação é estereosseletiva. Assim, propôs-se o desenvolvimento e validação de um método para análise dos enantiômeros do fármaco e seu metabólito em fração microssomal de fígado de ratos. O método foi desenvolvido empregando a cromatografia líquida de alta eficiência (HPLC) com detecção em 262 nm; a separação dos enantiômeros do fármaco e metabólito foi efetuada em uma coluna Chiralpak AD, empregando hexano: isopropanol: etanol (95:4:1, v/v/v) com 0,3% de dietilamina como fase móvel, na vazão de 0,9 mL min-1. A microextração em fase líquida (LPME) foi empregada como técnica de preparação das amostras e o método foi otimizado empregando planejamento fatorial. A seguinte condição final de extração foi selecionada: tempo de extração de 45 min, nenhuma adição de metanol ou NaCl, agitação da amostra a 4500 rpm, membrana de 6 cm de comprimento, fase doadora em pH 8,0 e ácido trifluoracético 0,1 mol L-1 como fase aceptora. O método mostrou ser linear na faixa de concentração de 312 - 5000 ng mL-1 para os enantiômeros da oxibutinina e 250 - 5000 ng mL-1 para os enantiômeros do metabólito. As recuperações foram de 61 e 55% para a (R)-oxibutinina e (S)-oxibutinina, respectivamente e de 70 e 72% para a (R)-N-desetiloxibutinina e (S)-N-desetiloxibutinina, respectivamente Obteve-se precisão com coeficientes de variação inferiores a 15% e exatidão com erros relativos menores que 15%. O método foi aplicado em um estudo de biotransformação in vitro empregando a fração microssomal de fígado de ratos. As constantes cinéticas foram determinadas e verificou-se uma pequena diferença de afinidade da enzima pelos enantiômeros da oxibutinina (Km= 9,3 nmol L-1 e 7,9 nmol L-1 para a (R)-oxibuinina e a (S)-oxibutinina, respectivamente), com maior afinidade à (S)-oxibutinina em função do menor valor de Km. / Oxybutynin is a chiral drug used as a racemate which, after oral administration, suffers pronounced liver biotransformation leading to the formation of N-desethyloxybutynin. This metabolite shows anticholinergic activity similar to the oxybutynin, contributing to the pharmacological effect and also with the adverse effects. Regarding the pharmacokinetic properties, some studies indicate the stereoselective biotransformation. Thus, it was proposed the development and validation of an enantioselective method for analysis of oxybutynin and its metabolite in rat liver microsomal fraction. The method was developed using high-performance liquid chromatography with detection at 262 nm; the separation of drug and metabolite enantiomers was performed on a Chiralpak AD column employing hexane: isopropanol: ethanol (95:4:1, v/v/v) plus 0.3 % diethylamine as the mobile phase, at a flow rate 0.9 mL min-1. Liquid phase microextraction was used for preparation of the samples and the method was optimized using factorial design; the following condition was established: extraction time of 45 min, no methanol and NaCl in donor phase, agitation of the sample at 4500 rpm, membrane of 6 cm in length, donor phase pH 8.0 and trifluoracetic acid 0.1 mol L-1 as aceptor phase. The method was linear over the range of 312 - 5000 ng mL-1 for oxybutynin enantiomers and over the range of 250 - 5000 ng mL-1 for the metabolite enantiomers. The recoveries were 61 and 55% for (R)-oxybutynin and (S)-oxybutynin, respectively and, for (R)-N-desethyloxybutynin and (S)- N-desethyloxybutynin 70 and 72%, respectively. Within-day and between-day assay precision and accuracy were lower than 15%. The method was applied to an in vitro biotransformation study using rat liver microsomal fraction. The kinetic constants were determined and there was a small difference in affinity of the enzyme for oxybutynin enantiomers (Km=9.3 nmol L-1 and 7.9 nmol L-1 for (R)-oxybutynin and (S)-oxybutynin, respectively), with higher affinity to the (S)-oxybutynin according to the lower value of Km